Apparent and standardized ileal amino acids digestibility for different protein feedstuffs fed at two dietary protein levels for growing pigs

Abstract Text: This study determined the apparent and standardized ileal amino acids digestibility (AID or SID) for growing pigs fed three protein feedstuffs with different fiber types at two dietary crude protein (CP) levels. Twenty boars (Yorkshire × Landrace) with 35 kg body weight and fitted with a simple T-cannula at the distal ileum were used. The treatments were three protein feedstuffs (soybean meal (SBM), canola meal (CM) or corn distillers dried grains with solubles, cDDGS) and two dietary CP levels (18 or 14%). Eighteen pigs were allocated to the experimental diets using a replicated 6 × 2 Youden square design. In each of the two experimental periods, two pigs were offered a nitrogen free diet to determine basal endogenous amino acid flow. Digesta was collected for two days after five days of adaptation. Reducing dietary CP level by 4% did not affect AID of DM and AA or SID of AA. Except for Met, Trp, Cys and Pro, AID for all the other AA were greater (P < 0.05) in the SBM diet compared with the CM diet. Apparent ileal digestibility for Gly and Asp was greater (P < 0.05) for the SBM diet compared with the DDGS diet. The AID for Ile, Leu, Phe, Val, Ala, Tyr and Asp was greater (P < 0.05) in the DDGS diet compared with the CM diet. There was protein feedstuff × protein level interaction (P < 0.05) for AID of Lys because in the diets with 18% CP, the AID of Lys was greater (P < 0.05) in the SBM and cDDGS diets compared with the CM diet, whereas the AID of Lys was not different among the protein feedstuffs in diets with 14% CP. Standardized digestibility was greater (P < 0.05) in the SBM diet compared with the CM diet for all AA except Trp and Pro, whereas the SID of Gly and Asp were greater (P < 0.05) in the SBM diet compared with the cDDGS diet. Standardized digestibility for Ile, Leu, Val, Ala, Tyr and Asp were greater in the cDDGS diet compared with the CM diet. It was concluded that differences in AA digestibility observed for the pigs were related to differences in chemical, including fiber, profiles of the protein feedstuffs used but independent of dietary CP level.

Keywords: amino acids, protein feedstuff, protein level